c_cpp 快速指数

Posted 2021-05-14

#include <iostream>
#include<bits/stdc++.h> 
using namespace std;

// #Theory #Math

long long fast_exp(long long base,long long exp){
    long long MOD=10000009;
    if(exp==1){
        return base%MOD;
    }else{
        if(exp%2==0){
            long long base1=pow(fast_exp(base,exp/2),2);
            return base1%MOD;
        }else{
            long long base2=base*pow(fast_exp(base,(exp-1)/2),2);
            return base2%MOD;
        }
    }
}

int main() {
    cout << fast_exp (2,5);
    return 0;
}